def ListToStr(mylist):
    str=''
    for item in mylist:
        if type(item) == type(''):
            str = str + item + ','
        if type(item) == type(1):
            str = str + int(item) + ','
    return str            
mylist=['this is my first item',0,'sina.com','2009-12-21 12:12:23',4]
mystr = ListToStr(mylist)
print mystr